...this is what we all try to do I guess. You said "I don't even look at other classes' code" but I always find it much easier to not look at a function's code

...this is what we all try to do I guess. You said "I don't even look at other classes' code" but I always find it much easier to not look at a function's code or at the code of a method of an immutable object or a "predicatively mutable" objects than for classes of highly mutable objects. ...that's why I'm currently investigating functional programming as way to make it easier to hold larger parts of programs in your head.